This invention relates to the manufacture of diagnostic strips of the kind used for diagnosis or monitoring of medical conditions. More particularly the invention relates to mechanism for transverse cutting of elongated cards to form a plurality of such strips and for separating out defective strips following the cutting operation.
Diagnostic strips are strips of paper, plastic or other sheet material which are coated with reagents that react to particular substances which may be present in biological fluids such as blood or urine. Typically such strips change color after being immersed in the biological fluid if the particular substance is present in the fluid. This enables a very quick, convenient and economical detection of many medical conditions and facilitates monitoring of patients. As one example, strips sensitive to glucose oxidaise are used in the diagnosis and monitoring of diabetes. Strips sensitive to certain hormones are used to detect pregnancy. Strips having other compositions detect a variety of other physiological conditions. Similar strips are also used for non-medical purposes such as for detecting the presence of particular chemical compositions in a fluid.
The diagnostic strip typically has a backing material formed of paper, plastic or the like to which the chemically sensitive coating material is applied. The coating material may be contained in one or more very thin tissues which are laminated on to the backing material. Applying the coating to each small strip individually would result in undesirably high manufacturing cost. This is avoided during manufacture by applying one or more long ribbons of the coating material to a lengthy piece of the backing material to form what is called a card. Cutting of the card along transverse cut lines produces the strips.
In some prior manufacturing processes the strips are produced by making simultaneous transverse cuts across the card using a rotary cutter having a row of spaced apart cutting disks disposed along an axis of rotation. The groups of strips which are produced simultaneously in this manner are then packaged or passed on to other mechanism for further processing. Prior U.S. Pat. No. 5,067,309 and prior U.S. Pat. No. 5,816,030 disclose examples of rotary strip cutting mechanism of this kind. In other prior manufacturing processes the strips have been produced sequentially by cutting successive strips from the card using a reciprocating cutting blade. Prior cutting mechanisms of either form do not enable performance of certain post cutting operations in a desirably efficient and economical manner.
Cards can on occasion have areas with visible manufacturing defects or areas which have been inadvertently contaminated with a foreign substance. Finished strips formed from such areas or containing portions of such areas may not function in the intended manner. The prior practice does not provide desirably efficient and economical arrangements for assuring that finished strips are free from defective areas of this kind. Individual inspection of each cut strip is at best a costly complication of the manufacturing process. Discarding of an entire card because of a small localized defective area results in wastage of other portions of the card material.
In many cases individual strips are emplaced in a housing formed of plastic or other material to form a kit which facilitates use of the strip. The housing may have openings for admitting fluid and for observing the effects of the fluid on the strip. Any mechanism for moving the cut strips from the cutter to the housings must bring the strips into precise registration with the housings as the strips typically are tightly fitted into recesses in the housings. The prior art does not provide desirably efficient and economical mechanism for this purpose.
The present invention is directed to overcoming one or more of the problems discussed above.
In one aspect of the present invention, apparatus for cutting transverse strips from an elongated card and for sorting defective strips from non-defective strips includes a die member having a shear zone defining edge across which successive transverse portions of the card may be traveled. A reciprocatable shear blade is adjacent to the die member and has a cutting edge which is positioned to cut transverse strips from the card at the shear zone defining edge in a sequential manner. A strip transporting carrier is supported for movement between a first location at which a front end of the carrier abuts the die member in position to receive and support strips which are cut from the card, a second location at which non-defective strips are removable from the carrier and a third location at which defective strips are released from the carrier.
In another aspect of the invention, apparatus for cutting transverse strips from an elongated card and for sorting defective strips from non-defective strips includes a die member having a horizontal slot into which successive transverse portions of the card may be traveled, the slot forming a shear zone defining edge. A shear blade is disposed against the die member and has a cutting edge positioned to cut transverse strips from the card at the shear zone defining edge as the blade is reciprocated in a vertical direction. The shear blade has an inclined surface which extends upward from the cutting edge and outward from the die member. A strip transporting carrier has a platen for supporting newly cut strips, the carrier being movable along a horizontal strip travel path which extends away from the shear zone defining edge of the die member. The carrier is movable from a first location at which a front end of the carrier is against the die member in position to receive and support a newly cut strip to a second location at which nondefective strips are removed from the carrier and is further movable to a third location at which defective strips are released from the carrier. The front end of the carrier is formed by a plurality of strip supports which are retractable into the platen portion of the carrier. The strip supports are urged into the platen by the inclined surface of the shear blade as the blade travels downward during a cutting operation. This moves the newly cut strip onto the platen.
The invention provides for economical and efficient sorting of defective diagnostic strips from non-defective strips after cutting of the strips from elongated cards which may include cards having defective areas. The strips are cut from the card in a sequential manner by a reciprocating shear blade. Each newly cut strip is received by a strip transporting carrier. The carrier moves non-defective strips to a first location at which they are picked off of the carrier for transfer to a housing or other processing. If the strip is a defective one continued motion of the carrier takes the strip to another location at which it is released into a waste receptacle. Structural features of the preferred form of the invention provide for precise positioning of the cut strips on the carrier at the pick up location thereby enabling precise registration of the strips with housings into which they are tightly fitted.